Batching system

ABSTRACT

A batching system for supplying weighted amounts of various aggregates, for instance to a concrete mixer, in which the bins for storing the aggregates and the weighing hoppers have at their bottom discharge ends an elongated slot opposite which is the top run of a conveyor, spaced from said slot and which serves to close the bin or hopper and to convey the material to other equipment in such a way that shearing of the mass of material is effected at the slot level so as to eliminate friction between the conveyor and the material. The weighing hoppers for the various aggregates are arranged in association with a common conveyor which, in combination with the hoppers, effect preliminary mixing of the various aggregates to diminish the mixing time in the concrete mixer.

United States Patent Gagnon et al.

[54] BATCHING SYSTEM [72] Inventors: Pierre Gagnon, 5637 Wilderton .Ave.; Pierre Laiorest, 1945 Bruxelles St., both of Montreal, Quebec, Canada [22] Filed: July 6, 1970 [21] Appl.No.: 52,348

[52] U.S.Cl. ..l98/54 [51] Int. Cl. ..B65g 47/18 [58] Field 01 Search ..l98/39, 44, 47, 53-54, 198/56-58, 184

[56] References Cited UNITED STATES PATENTS 2,278,730 4/1942 Neuman ..l98/56 219,911 9/1879 Clark. ..l98/47 X 756,600 4/1904 Dodge ..198/108 X 2,642,979 6/1953 Beech ..-l98/56 [151 3,701,409 [451 Oct. 31, 1972 FOREIGNrATENTS on APPLICATIONS 730,075 5/1955 Great Britain Primary Examiner-Edward A. Slroka Attorney-Pierre Lesperance [57] ABSTRACT A batching system for supplying weighted amounts of various aggregates, for instance to a concrete mixer, in

which the bins for storing the: aggregates and the weighing hoppers have at their bottom discharge ends an elongated slot opposite which is the top run of a conveyor, spaced from said slot and which serves to close the bin or hopper and to convey the material to other equipment in such a way that shearing of the mass of material is effected at the slot level so as to eliminate friction between the conveyor and the material. The weighing hoppers for the various aggregates are arranged in association with a common conveyor which, in combination with the hoppers, effect preliminary mixing of the various aggregates to diminish the mixing time in the concrete mixer.

6 Claims, 10 Drawing Figures pmmEflnma'l I972 3,701,409

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PATENTED 110131 I972 me A l AGENT INVEN mes Pierre GAG/VON Pierre L A F OPE 5 T BY WW4,

PATENTED U 31 1973 3. 7 O1. 409

sum 5 0r 6 INVENTORS Pier/"e GAGNON Pierre LAFOREST AGENT PATENTEDucm 1912 sum s or 6 mmJ INVENTORS Pierre GA e/vo/v Pierre LAFOREST BY QM AGENT BATCHING SYSTEM The present invention relates to equipment for the handling of granular material and, more particularly, to a system for storing and delivering weighed amounts of various aggregates to a concrete mixer in a concrete mixing plant to make, for instance, concrete blocks.

The various aggregates for making concrete have to be stored in large bins and transferred to weigh hoppers and other equipment.

It is known to close the discharge mouth of said bins and hoppers by a belt conveyor, which, upon its operation, feeds the material to another material handling apparatus.

The belt conveyor thus acts as a closure for the bins; however, in known bin and belt conveyor combination, the belt conveyor top run is very close to the lips of the mouth of the bin and the latter has an opening or notch at the downstream wall of the bin with respect to the direction of travelling of the belt conveyor. This downstream opening is normally provided with an adjustable gate to control the flow. The material discharges at the downstream end of the hopper mouth and the upstream material is fully supported by and is in frictional contact with conveyor belt, requiring high horsepower to drive the belt and resulting in rapid wear of the latter. Therefore, in practice, known bins are of circular or substantially square shape so as to have a similarly shaped mouth to keep wear of the belt and the horsepower requirements within acceptable limits. However, this results in high bins for a given capacity requiring extensive support structure or deep excavation. a

In conventional batching systems, the various aggregates, after weight and/or volume measuring, are fed along separate paths into a silo, which thereafter feeds the material to the concrete mixer. Therefore, the aggregates in the silo are not mixed, or very slightly mixed, requiring a longer mixing time in theconcrete mixer.

The main object of the invention resides in the provision of a bin or hopper for granular material, which is of elongated shape with an elongated mouth and which is provided with a feeder conveyor along said discharge mouth, the assembly of the bin and conveyor being so arranged that there is no relative movement between the conveyor belt and the material in direct contact with the conveyor, resulting in much less wear of the conveyor belt and in reduced horsepower requirements.

Another object of the invention resides in the provision of a weighing and/or volume measuring system for the various aggregates, which produces preliminary mixing of the aggregates during their feeding to a storage bin or silo prior to the mixing of said aggregates with the cement, therefore reducing the mixing time in the concrete mixer.

Another important object of the present invention resides in the provision of a batching system of the character described, in which the storage bins for the various aggregates can have a much larger capacity for a given height than conventional storage bins.

The foregoing and other objects of the invention will become more apparent during the following disclosure and by referring to the drawings, in which:

FIG. 1 is a schematic top plan view of the general layout of a plant for making concrete blocks and showing how the batching system of the invention is integrated in said plant;

FIG. 2 is a view taken along line 2-2 of FIG. 1, but with the excavation retaining walls removed, and show ing in elevation the front or downstream ends of a plurality of side-by-side storage bins, each for receiving one type of aggregate;

FIG. 3 is a side elevation taken along line 3-3 of FIG. 2 showing one storage bin with its associated belt conveyor andalso showing in cross-section one of the weigh hoppers and associated conveyor;

FIG. 4 is a broken side elevation of the series of weigh hoppers;

FIGS. 5 and 6 are partial vertical sections, taken along lines 5-5 and 6-6 respectively of FIG. 4;

FIG. 7 is a top plan view of a weigh hopper and associated common conveyor belt, said view taken along line 77 of FIG. 6;

FIG. 8 is an end elevation of one weigh hopper arrangement and showing in cross-section the belt conveyor and framework common to the various weigh hoppers;

FIG. 9 is a side elevation of the system of FIG. 8; and

FIG. 10, shown on the first sheet of drawings, is a partial view of the downstream end of a storage bin with a trough conveyor in cross-section.

In the drawings, like reference characters indicate like elements throughout.

FIG. 1 shows one possible application of the batching system of the invention. FIG. ll shows the general layout of a plant for making concrete blocks.

Building 1 houses a plurality of storage bins 2, of elongated shape, disposed side by side, each for one type of aggregate and adapted to receive the aggregates from trucks T wheeled over the bins 2. Each bin 2 discharges the material unto a belt conveyor 3, which discharges the material into weigh hoppers arranged above a common belt conveyor 4, the latter disposed across the discharge ends of all the conveyors 3.

Conveyor 4 discharges the weighed aggregates of the particular types desired into a skip 5, which elevates the mixture of aggregates and discharges the same into a reservoir or bin 6 holding one batch of aggregate. This batch is fed by conveyor 7 to a concrete mixer 8, also fed with cement from a silo 9. The properly mixed concrete is discharged into a skip 10 and loaded into a hopper l1.

Hopper 11 is common to two concrete block machines 12, the concrete mixture being fed to any one of said machines by a swinging conveyor 13. The molded blocks are conveyed on pallets by conveyors 14 to an automatic loader-unloader arrangement 15, which includes an elevator 16 which lowers the fresh blocks into an annular underground block curing boat 17 floating in water in a tunnel 18 and driven into slow rotation by a boat turning mechanism 19. After one rotation of the boat, the blocks are cured and are lifted off the boat by elevator 16 and unloaded by the loaderunloader 15 unto a conveyor 20. The pallets are removed from under the cured blocks by a pallet stripper 21 and returned by conveyor 22 to the concrete block molding machines 12. The cured concrete blocks are fed to an automatic block cuber 23 in which the blocks are stacked in cube form on large pallets and carried away on cars movable in a closed circuit along the path indicated at 24.

On the outside of the building 25 housing the abovedescribed machines, the cured palletized blocks are picked up at station 26, while, at station 27, new pallets 'are deposited on the cars which return and move 7 through the cuber 23.

The present invention is particularly concerned with the equipment, and machines located in building 1 for storing the various aggregates, weighing and premixing the same before they are discharged to the skip 5. Referring to FIGS. 2 and 3, each type of aggregate is discharged by trucks T into a separate storage bin 2.

The truck T is backed up unto a grille composed of a plurality of transverse beams 28 which have their flanges sufficiently spaced for the passage of the granular free flowing material M serving as an aggregate for the manufacture of the concrete. The granular material M flows through the grille into the underlying storage bins 2. The bins 2 are located in an underground chamber 29 so as to provide grille 28 at ground level 30. Each bin 2 is longitudinally inclined and is composed of side walls3l equally converging downwardly and terminating; the angle made by side walls 31 with the vertical is smaller than the angle of repose relative to the vertical of the free flowing granular material M. Side walls 31 terminate short of each other at their lower longitudinal straight edge 32 to define an elongated substantially rectangular opening of discharge mouth 33, said mouth further being defined by the lower edge 34 of the upstream or back transverse end wall 35 of the bin and by the lower edge 36 of the downstream front end wall 37 of the bin. Edges 32 and 34 are straight and preferably lie in a common plane. Downstream edge 36 may be straight and lie in the lastmentioned common plane or be notched to form a concave lower free edge, as shown at 79, for downstream wall 37' of modified bin 2, as shown in FIG. said concave edge 79 defines an end opening above the level of edges 32 of side walls 31.

The side walls 31 are reinforced by transverse and longitudinal beams 38 and 39. The end walls 35 and 37 are inclined; the top of the inclined side walls 31 is extended to the grille 28 by vertical walls 40. Similarly, end wall 35 is extended to the underside of the grille 28 by vertical end wall 41. Each bin is supported by posts 42 and in turn supports the I beams 28. The several bins are interconnected by junction beams 43.

The belt conveyor 3 is disposed underneath the mouth 33 of each bin with its top belt run 44 spaced from and parallel to the longitudinal edges 32 of the mouth 33. The top run moves from the upstream end 35 to the downstream end 37 of the bin 2 to discharge the material 29 into a weigh hopper 45 disposed just above the belt conveyor 4.

In accordance with a main feature of the present invention, the bin 2 starts to discharge from its upstream end or close to end wall 35, when the conveyor 3 is operating and not from its downstream end or close to end wall 37. This means that the material discharged from the upstream end of the bin moves along with the conveyor belt past the material in the remaining portions of the bin.

In practice, a ribbon of material is moved by the belt along the entire length of the bin when the latter is full or along that longitudinal portion of the bin which contains material when the bin is partially empty.

The ribbon normally takes a cross-section with downwardly diverging side edges and a convex top edge substantially mating concave edge 79 of FIG. 10. This is why downstream edge 36, shown in FIG. 2, is preferably made concave, as shown at 79 in FIG. 10. This permits free passage of the above-noted ribbon of material.

To obtain this upstream discharge of material, the width of discharge mouth 33 is selected so as to produce an arching effect in the material at the level of mouth 33. Thus, there is a sharp drop of internal static pressure in the material downwardly across the mouth and this pressure increases again under gravity down to conveyor belt level. Consequently, the coefficient of friction between the material and the conveyor belt is greater than the coefficient of friction within the material at the level of the mouth and a shearing action takes place at mouth level.

The width of discharge mouth to be selected is a function of the slope of the bin side walls 31 and of the free flowing characteristics of the material being handled. For instance, for a wall slope of about 50 and for the types of aggregates normally used for making concrete blocks, such as gravel, sand and pumice, the width of mouth is preferably 8 inches and may vary between 4 inches and 10 inches. Obviously the width of mouth 33 must not be too small otherwise the arching effect would be too great and material discharge from the bin will be prevented. Therefore, the arching effect must be present but the material must yet have a tendency to discharge. Discharge is prevented by the ribbon of material on the conveyor belt which acts as a plug and supports the material in the bin.

As the upstream end of the conveyor belt becomes empty, material in the upstream end of the bin immediately discharges on the belt and replenishes the ribbon.

The slope of lateral walls 31 is as normally found in conventional bins. The downward convergence of the bin lateral walls must be sufficient for said walls or for the stationary material in the bin to produce the aforementioned arching effect by increasing transverse pressure exerted on the material moving down the bin.

The conveyor 33, together with the plane of mouth 3, may be horizontal or inclined up to about 15 or more to the horizontal, in the downstream direction, as long as the ribbon material is transported by the inclined conveyor.

The conveyor belt top run may be transversely flat, as shown in FIGS. 5 and 6, or may be trough shaped, as shown in FIG. 10, wherein trough conveyor belt 3' is supported by conventional trough roller assemblies 78 mounted on brackets 79.

The spacing between the top run of the conveyor belt and the mouth 33 is selected in accordance with the rate of flow desired for a given speed of the conveyor belt; the greater the spacing the larger is the flow.

The width of the conveyor belt must be sufficient to prevent overflow of the material due to the natural lateral inclination taken by the same in its free zone below the mouth 33.

Apart from the reduction in the conveyor belt wear and in the horsepower requirements and, consequently, in making it possible to provide an elongated low bin as noted above, the feature of the back or upstream discharge of the bin enables a most convenient arrangement of the conveyors systems and of the arrangement for replenishing the bins.

As shown in FIG. 3, it is possible to incline the bin upwardly towards its downstream front end and arrange the weigh hoppers 45 together with the conveyor 4 on the same floor level 46, as chamber 29 with the bins being capable of being completely unloaded.

The bins 2 can be filled completely and with the material above the grille 28 as high as the truck T can dump the material and over the entire length of the bin. The material above grille 28 will gradually flow down starting from the entrance of the building 1 housing the bins and, consequently, the truck T can back up over the grille so as to always fill the bin from the downstream end first. With this arrangement, long time intervals may be had between successive bin refilling and the refilling may be effected even when the bin is not completely empty.

Another advantage of the upstream discharge feature of the bin in accordance with the invention is the fact that the rate of flow of the material being discharged is much more constant than in known systems in which downstream discharge takes place. This is an important feature when the material is discharged into a weighing or volume measuring system.

In the arrangement described, the aggregates discharged from the bins 2 are transferred to a weighing system wherein they are individually weighed to a predetermined amount and then premixed and transferred to a storage bin. 7

Each weigh hopper 45 has inclined downwardly converging straight side walls 47 protruding outwardly from end walls 48,49. The side walls 47 are reinforced by transverse webs 50. The lower edge of the side walls 47 and of the upstream end wall 48 and the downstream end wall 49 are disposed in a common flat plane. However, the lower edge of downstream wall 49 may be notched, as shown at 79 in FIG. 10. An inverted V-shaped elongated tunnel member 51 extends longitudinally of the hopper, is secured to the end walls 48,49 and to webs 50. The longitudinal edges of the dividing member 51 are in the same plane as the longitudinal lower edges of the side walls 47 and end walls 48,49, so as to define a discharge mouth made of two elongated longitudinally extending mouth sections 52.

The end walls 48,49 have their lower edge forming a V-shaped recess 53 opposite the tunnel member 51. The portions of the side walls 47 extending outwardly of the downstream and wall 49 serve to support outwardly converging baffles 54 which are in close proximity with the top run of the conveyor belt '4 and serves to move centrally of the conveyor belt the material discharged through the two mouth sections 52 of the hopper.

The top run of the conveyor belt 4 is supported on a flat steel plate 55 which is spaced below the plane containing the two mouth sections 52, so that the top conveyor belt run is spaced below said sections 52.

The conveyor belt is wider than the overall width of the openings 52 and tunnel member 51, so as to retain therein material which issues from the hopper and takes a natural inclination on the sides. Friction of the belt on the support plate 55 is minimized by providing an air cushion between the belt and plate. This air cushion is formed by compressed air supplied to a conduit 56 secured underneath the plate 55 and in communication with the underside of the belt through longitudinal central rows of holes 57 made in plate 55.

As shown in FIG. 8, the plate 55 is supported by a framework 58, in turn suspended from the sides of the hoppers through legs 59 and tie bolts 60. The spacing between the conveyor belt top run and the mouth 52 can be adjusted by means of nuts 60' screwed on tie bolts 60. The assembly of the hopper 45, steel plate 55, framework 58 and top belt run 4 is suspended from a known scale system 61 and the latter is suspended by tie bolts 62 from a top main framework 63, which is supported by main legs 64 on a ground-supported base frame 65, which also supports rollers 66 for the return bottom run 67 of the conveyor 4.

As shown in FIG. 4, the conveyor 4 is driven by a suitable drive, indicated at 68, which may include an electric motor and a speed reducing unit driving the main drum 69. The endless belt, preferably made of rubber, is maintained under suitable tension by a tensioner system 70 at the other end of the conveyor. The conveyor 3 for each bin 2 is similar to conveyor 4; it has a flat support plate and air cushion system and the top belt run 44 is maintained in a flat plane parallel to and spaced from the plane of mouth 33'.

The conveyor belt 4 is common to a plurality of weight hoppers 45, the latter being longitudinally aligned; one hopper 45 is associated with each bin 2. Each hopper 45 is suspended from one scale mechanism 61 together with its associated supported plate 55 supporting the portion of belt 4 extending thereover. Thus, the material in each hopper is weighed independently of the material in the other hoppers. Because belt 4 is flexible, its portion extending between the various hoppers will not influence the precision of the weighing of the material in any one given hopper.

To prevent longitudinal sway of the hoppers especially when conveyors 4 is operating, while not influencing the precision of the weighing, the different hoppers are loosely attached one to the other by chains 71 while a post '72 is rigidly secured to base frame 65, intermediate legs 59 of the weigh hopper assembly, and is attached to said legs 59 by chain 73.

Preferably the weighing mechanism 61 automatically controls the operation of the bin conveyor 3. More specifically, the bin conveyor 3 is manually started, the material flows into the associated weigh hopper 45, and when the desired weight of material has been received in the hopper 45, the scale beam 74 tips and opens a switch, not shown, which cuts off the contact of the electric drive of conveyor 3. For more accurate weighing, a two-beam type scale system is provided, wherein the adjustable weight 75 of the main beam 74 is adjusted to a weight slightly below the final desired weight to open a first switch which slows down the conveyor 3 to reduce the rate of flow and the second scale beam will cut off a second circuit upon the exact weight being obtained to stop completely the conveyor 3.

Once the various aggregates have been weighed in their associated hoppers 45 with all the conveyors 3 being stopped, the conveyor 4 is started to convey the various aggregates into the common skip 5.

Due to the arrangement of the various hoppers 45 longitudinally of the common conveyor 4 and because the weigh hoppers discharge simultaneously unto said conveyor 4, it will be appreciated that a certain premixing of the aggregates will be automatically carried out as the aggregates of the various types are discharged simultaneously into the skip 5.

During movement of the conveyor, the material being discharged from an upstream trailing or left and hopper with respect to the direction of discharge of the material, as shown in FIG. 4 and by arrow 76 in FIG. 7, will hit the material being discharged from the next downstream or right-hand hopper and flow along the last-named material.

In order to further facilitate premixing of the aggregates, a certain quantity of the material discharged from an upstream hopper will flow through the inverted V-shaped tunnel member 51 of the downstream hopper.

To guide the material of a trailing hopper discharged from an upstream hopper into the tunnel member 51 of a downstream hopper, each hopper at its downstream end is provided with the inclined baffles 54 which narrow down the stream of material discharged from one hopper to facilitate the passage of said material through the tunnel 51 of the next hopper along the direction of discharge.

As for the conveyor belt and bin arrangement 3,2, the weigh hoppers 45 start to discharge from their back or upstream end and shearing of the material is effected substantially at the level of the mouth sections 52, whereby there is practically no friction exerted on the belt 4, because the material in contact therewith moves along with the belt.

As previously noted, the spacing between the belt 4 and the mouth sections 52-of the various hoppers can be adjusted and said spacing may be different from one hopper to the other, depending on the type of aggregates being weighed and discharged and depending on the location of the particular hopper along the row of hoppers, and this in order to provide as thorough premixing of the various aggregates as possible. For instance, the above-noted spacing can be progressively greater in the direction of conveyor movement, so that a layer of material from a downstream hopper will be deposited on the layer coming from the next upstream hopper, resulting in further premixing of the aggregates.

The premixing of the aggregates will substantially reduce the mixing time of said concrete mixer 8. Obviously, the various hoppers 45 need not be of the same length and the width of their discharge openings 52 may vary.

The system of the invention, while having been described as particularly applicable to the handling, weighing and premixing of various aggregates for making concrete, can be used in other types of systems for any type of handling granular material.

Any type of granular material may be handled by the equipment of the invention as long as it will flow under gravity. Thus, the term granular material includes powder material; for instance portland cement in dry state can be handled by the system of the invention.

Referring to weigh hoppers 45, it is noted that the mouth sections 52 permit to make the hoppers wider and, consequently, lower for a given length and capacity.

Although belt 4 is shown transversely flat, it may have a trough shape as belt 3' of FIG. 10.

Although the downstream end walls 49 of hoppers 45 are shown with a straight lower edge, this edge may be concave, as shown by edge 79 of FIG. 10.

The hoppers 45 may be used to measure the volume of the aggregates instead of their weight, if volume measuring is preferred. A sensing plate (not shown) is pivotally suspended from a bracket carried by the hopper and is pivoted by the material finally reaching it during filling of the hopper. Pivoting of the sensing plate operates a switch to stop operation of bin conveyor 3. If only volume measuring is desired, it is obvious that the scale system 61 can be dispensed with and that the hoppers 45 can be directly suspended from framework 63 or secured to legs 64.

As a further modification one could provide for the simultaneous measuring of the weight and volume of the material in hopper 45 giving data for calculating the density of the material, if such information is desired.

What we claim is:

1. A feeder system for granular material, comprising a plurality of elongated hoppers disposed longitudinally in end-to-end relationship in a row, each adapted to receive granular material, an underframe suspended from each hopper, each hopper having at least one elongated discharge mouth at its bottom, a belt conveyor having a belt top run supported by the underframe of each hopper, extending longitudinally of all said hoppers opposite said respective mouths and spaced therefrom and wider than the width of said mouths to prevent discharge of material in the hoppers when the conveyor is stopped, the material flowing out of the hoppers and off said conveyor when the conveyor is in operation, each said hopper having downwardly converging longitudinal walls having straight, parallel lower free edges defining the longitudinal sides of said month, said underframe being adjustably connected to the hopper to vary the spacing between said belt top run and said hopper discharge mouth, and wherein the elongated discharge mouth of each hopper is divided in two elongated mouth sections by an elongated member of inverted V-shaped crosssection defining a tunnel for the passage between said mouth sections of material transported by said conveyor, and wherein each hopper is provided with centrally converging baffles at the downstream end thereof corresponding to the direction of movement of the conveyor belt top run, said baffles disposed opposite the respective elongated mouth sections to direct the material discharged from the two mouth sections of an upstream hopper, centrally of the belt, so as to flow through the elongated tunnel member of a downstream hopper.

2. A feeder system for free flowing granular material comprising, in combination, a bin of elongated shape having equally inclined downwardly converging longitudinal side walls with straight substantially parallel lower free edges spaced from each other to define a centrally located discharge mouth at the bottom of said bin, the angle made by said longitudinal walls with the vertical being smaller than the angle of repose relative to the vertical of the free flowing granular material which said bin is adapted to contain, the width of said mouth being smaller than the width which would allow free discharge of the material through said mouth, and is such that said material in the bin has a tendency to arch across said mouth, and a belt conveyor extending longitudinally of said bin under the same and opposite said mouth with the top run of said belt conveyor substantially uniformly vertically spaced from said lower free edges, the conveyor belt being wider than said mouth so as to retain thereon the material discharged through said mouth, said conveyor preventing discharge of said material when stationary and movement of said conveyor causing discharge of material from said bin starting from the upstream end of said bin in relation to the direction of the conveyor movement and the material in direct contact with said conveyor having substantially no movement relative to said operating conveyor.

3. A-feeder system as claimed in claim 2, wherein said bin has a downstream end wall with a concave lower free edge defining an end opening above the level of said lower free edges of said longitudinal side walls.

4. A feeder system as claimed in claim 2, wherein said lower free edges of said longitudinal side walls and said conveyor are upwardly inclined with respect to the horizontal in the discharging direction of said conveyor.

5. A feeder system as claimed in claim 2, wherein there is a plurality of elongated bins disposed longitudinally in end-to-end relationship in a row above said belt conveyor which is common to all of said bins, the elongated discharge mouth of each bin being divided in two elongated mouth sections by an elongated member of inverted V-shape cross-section defining a tunnel for the passage between said mouth sections of material transported by said conveyor.

6. A feeder system as claimed in claim 5, wherein each bin is provided with centrally converging baffles at the downstream end thereof corresponding to the direction of movement of the conveyor belt top run, said baffles disposed opposite the respective elongated mouth sections to direct the material discharged from the two mouth sections of an upstream bin centrally of the bin, so as to flow through the elongated tunnel member of a downstream bin. 

1. A feeder system for granular material, comprising a plurality of elongated hoppers disposed longitudinally in end-to-end relationship in a row, each adapted to receive granular material, an underframe suspended from each hopper, each hopper having at least one elongated discharge mouth at its bottom, a belt conveyor having a belt top run supported by the underframe of each hopper, extending longitudinally of all said hoppers opposite said respective mouths and spaced therefrom and wider than the width of said mouths to prevent discharge of material in the hoppers when the conveyor is stopped, the material flowing out of the hoppers and off said conveyor when the conveyor is in operation, each said hopper having downwardly converging longitudinal walls having straight, parallel lower free edges defining the longitudinal sides of said mouth, said underframe being adjustably connected to the hopper to vary the spacing between said belt top run and said hopper discharge mouth, and wherein the elongated discharge mouth of each hopper is divided in two elongated mouth sections by an elongated member of inverted V-shaped cross-section defining a tunnel for the passage between said mouth sections of material transported by said conveyor, and wherein each hopper is provided with centrally converging baffles at the downstream end thereof corresponding to the direction of movement of the conveyor belt top run, said baffles disposed opposite the respective elongated mouth sections to direct the material discharged from the two mouth sections of an upstream hopper, centrally of the belt, so as to flow through the elongated tunnel member of a downstream hopper.
 2. A feeder system for free flowing granular material comprising, in combination, a bin of elongated shape having equally inclined downwardly converging longitudinal side walls with straight substantially parallel lower free edges spaced from each other to define a centrally located discharge mouth at the bottom of said bin, the angle made by said longitudinal walls with the vertical being smaller than the angle of repose relative to the vertical of the free flowing granular material which said bin is adapted to contain, the width of said mouth being smaller than the width which would allow free discharge of the material through said mouth, and is such that said material in the bin has a tendency to arch across said mouth, and a belt conveyor extending longitudinally of said bin under the same and opposite said mouth with the top run of said belt conveyOr substantially uniformly vertically spaced from said lower free edges, the conveyor belt being wider than said mouth so as to retain thereon the material discharged through said mouth, said conveyor preventing discharge of said material when stationary and movement of said conveyor causing discharge of material from said bin starting from the upstream end of said bin in relation to the direction of the conveyor movement and the material in direct contact with said conveyor having substantially no movement relative to said operating conveyor.
 3. A feeder system as claimed in claim 2, wherein said bin has a downstream end wall with a concave lower free edge defining an end opening above the level of said lower free edges of said longitudinal side walls.
 4. A feeder system as claimed in claim 2, wherein said lower free edges of said longitudinal side walls and said conveyor are upwardly inclined with respect to the horizontal in the discharging direction of said conveyor.
 5. A feeder system as claimed in claim 2, wherein there is a plurality of elongated bins disposed longitudinally in end-to-end relationship in a row above said belt conveyor which is common to all of said bins, the elongated discharge mouth of each bin being divided in two elongated mouth sections by an elongated member of inverted V-shape cross-section defining a tunnel for the passage between said mouth sections of material transported by said conveyor.
 6. A feeder system as claimed in claim 5, wherein each bin is provided with centrally converging baffles at the downstream end thereof corresponding to the direction of movement of the conveyor belt top run, said baffles disposed opposite the respective elongated mouth sections to direct the material discharged from the two mouth sections of an upstream bin centrally of the bin, so as to flow through the elongated tunnel member of a downstream bin. 